Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!mailrus!ukma!cwjcc!bammi@dsrgsun.ces.CWRU.edu From: bammi@dsrgsun.ces.CWRU.edu (Jwahar R. Bammi) Newsgroups: comp.sys.atari.st Subject: Re: Networking, ST's and Spectre 128 Message-ID: <103@cwjcc.CWRU.Edu> Date: 30 Sep 88 20:57:57 GMT References: <3602@druhi.ATT.COM> Sender: news@cwjcc.CWRU.Edu Reply-To: bammi@dsrgsun.ces.CWRU.edu (Jwahar R. Bammi) Organization: Case Western Reserve University Lines: 24 In-reply-to: dlm@druhi.ATT.COM (Dan Moore) In article <3602@druhi.ATT.COM>, dlm@druhi (Dan Moore) writes: > > If you have an SCC connected to the STs cartridge port it can >not be interrupt driven, it must be polled by the CPU on a regular >basis so that it can detect incoming data. So you need to setup one of >the hardware timers to interrupt the CPU 28K times per second (actually >it needs to be at least 50% faster than that in order to be sure no >data is lost) so it can check if a data byte has arrived and if it needs >to feed the transmitter another byte. This would occur *ALL* of the >time, whether or not the AppleTalk link is active. This would slow down >the Spectre 128 a lot, maybe even make it unusable. > Well thats true if you take the Apple `lets do everything in software' approach. The other alternative is to use buffers from/to which the CPU can transfer data as needed. In fact, it is conceivable that all the packetiztion etc be done by a simple processor, and then shipped thru the cart. port., a packet worth at a time, or at some appr. granularity. -- usenet: {decvax,sun}!cwjcc!bammi jwahar r. bammi csnet: bammi@dsrgsun.ces.CWRU.edu arpa: bammi@dsrgsun.ces.CWRU.edu compuServe: 71515,155